function setCanvas(map) {
  const canvas = document.createElement("canvas");
  let size = 40;
  canvas.width = size;
  canvas.height = size;
  let radius = size / 4;  //10;
  let increase = true;
  let ctx = canvas.getContext("2d");
  function draw() {
      ctx.clearRect(0, 0, size, size);
      /* 第一个圆 */
      ctx.beginPath();
      ctx.arc(size / 2, size / 2, radius, 0, Math.PI * 2);
      ctx.closePath();
      ctx.fillStyle = "#ff2d51";
      ctx.fill();
      /* 设置第二个圆 */
      ctx.beginPath();
      ctx.arc(size / 2, size / 2, 8, 0, Math.PI * 2);
      ctx.closePath();
      ctx.fillStyle = "#0D5EFF";
      ctx.fill();
      if (radius > 14) {
          increase = false;
      }
      if (radius < 10) {
          increase = true;
      }
      if (increase) {
          radius++;
      } else {
          radius--;
      }
      setTimeout(draw, 100);
      map.render(); //让地图重新渲染一下
  }
  draw();
  return canvas;
}